Then again, you already have. He’s your neighbor. Or maybe he’s your friend. You’ve borrowed his tools, and he’s borrowed yours. Your kids have played with his. You’ve chatted amiably and often … over the fence, at the store, at church, on the bus. You think you know him.

But you don’t. Not really.

Same with Sheila. You’ve known her for ages. You’ve shopped with her, carpooled with her, swapped doctor stories with her and worked with her in the PTA. You’ve even done a few things socially with her and her husband. You like her. A lot.

But you don’t really know her. If you did, you’d know that she’s ill. So is Ben. Their respective illnesses are not the same, yet there are a lot of similarities. Both require frequent visits to well-trained specialists. Both take daily doses of powerful, expensive medications. Both struggle with the limitations imposed upon them by their infirmity. And both are reluctant to talk about it for fear of what people might say.

That’s why you probably don’t even know about it. Oh, you’ve noticed that Ben gets a little down in the dumps from time to time. And emotionally, Sheila goes up and down like a yo-yo. Sometimes she’s the most delightful woman in town, and sometimes she looks as though she’d bite your hand off if you reached out to her.

“That’s just Ben,” you’ve reasoned. And “That’s just the way Sheila is.”

But it isn’t. The real Ben is warm and witty, carefree and compassionate. The real Sheila is absolute bedrock — solid and secure and yet gentle and loving. Whenever you see something else in them, you’re seeing the illness. Or the medication. Or maybe a combination of the two.

But it isn’t them. Not really.

Ben and Sheila are mentally ill. Which is not to say their illness is all in their heads. Mental illness is just as real and can be just as debilitating as the most devastating physical maladies. It binds it victims in transparent chains and holds them securely in prisons without walls. But because their infirmity can’t be seen or measured physically, many of us are inclined to dismiss mental illness as a cop-out or a sign of weakness or lack of effort — especially when we see it in people who appear to be … well … normal.

You know. Like us.

Ben certainly seems that way. He’s got a great family, a lovely home and a good, secure job in a profitable field. He’s got no reason in the world to be depressed. But he is. Chronically. The medication helps some, but he still battles his personal demons daily. And privately. Only occasionally does it show through the facade he has learned to hide behind.

“I have a good life,” Ben told me recently. “I love my family, and I’m grateful for what I have. I don’t know why I’m depressed. I just am. And telling me to be happy is like telling a bald person to grow hair. You can’t do it if you don’t have it. And right now, I don’t have it.”

Neither does Sheila — not that you’d know it by taking a superficial look at her life. Her family is lovingly loyal to her and to each other. She is active and involved in her church, and she works hard to keep her home and family together. But everywhere she goes she carries the physical and emotional scars of the horrifying abuse she endured throughout her childhood.

“I’m getting better — really, I am,” she says. “Most of the time I’m OK. But once in a while … I don’t know … I just can’t handle it.”

Whatever “it” is.

“I’m not trying to make excuses,” Ben said. “I’d just like to feel that people know I’m doing the best I can — and that they don’t judge me too harshly when my best isn’t enough.”